Drive system for imaging device

ABSTRACT

A drive mechanism for a mobile imaging system comprises a main drive geared into a drive wheel for propelling the imaging system, including a base and one or more imaging components, across a surface. The drive mechanism can also include a scan drive that moves the drive mechanism and the one or more imaging components along an axis relative to the base to provide an imaging scan, and a suspension drive that extends the drive wheel relative to a bottom surface when the imaging system is in a transport mode and retracts the drive wheel relative to the bottom surface of the base when the imaging system is in an imaging mode. The drive wheel supports the weight of the imaging components, but does not directly support the base assembly, which can include pedestal and tabletop support. One or more casters located on the base can support the weight of the base assembly.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.61/313,299, filed Mar. 12, 2010, the entire contents of which areincorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

N/A

BACKGROUND OF THE INVENTION

Conventional medical imaging devices, such as computed tomography (CT)and magnetic resonance (MR) imaging devices, are typically fixed,immobile devices located in a discrete area reserved for imaging that isoften far removed from the point-of-care where the devices could be mostuseful.

It would be desirable to make these imaging devices mobile, so that theycan move to various locations within a hospital or other health servicesenvironment. This is difficult due to the size, weight and overallnumber of components required for making an operable imaging system, andeven a relatively small and compact imaging device, such as an x-ray CTscanner, can weigh upwards of 2500 lbs.

There is a need to improve the mobility of imaging systems withoutsacrificing image quality or adding significantly to the size and weightof the device.

SUMMARY OF THE INVENTION

A drive mechanism for a mobile imaging system comprises a drive wheel,and a main drive geared into a drive wheel for propelling the imagingsystem across a surface in a transport mode. The imaging system includesa base and one or more imaging components. The drive mechanism furthertranslates one or more imaging components along an axis relative to thebase in an imaging mode, where the one or more imaging components aresupported by the drive wheel in both the transport mode and the imagingmode.

The drive mechanism can further comprise a scan drive that translatesthe one or more imaging components along an axis relative to the base toprovide an imaging scan, and a suspension drive that extends the drivewheel relative to a bottom surface of the base when the imaging systemis in a transport mode. The suspension drive retracts the drive wheelrelative to the bottom surface of the base when the imaging system is inan imaging mode.

According to one aspect, the drive wheel supports the weight of theimaging components, but does not directly support the base assembly,which can include a pedestal and tabletop support. One or more casterslocated on the base can support the weight of the base assembly.

The drive mechanism can be positioned within the base, preventinginterference with a patient table shuttle when driving up to the baseand also preventing interference with an operator's feet while standingat the table.

During scanning, the drive wheel supports the weight of the imagingcomponents, which can be located on a gantry positioned above the drivemechanism. The base is positioned on the floor, on at least threesupport pads attached to the bottom of the base that define a scanningplane, which minimizes or eliminates deflection of the base duringscanning due to an uneven floor surface.

In an imaging mode, the drive wheel and casters retract to allow thebase to sit on the support pads to create a scan plan. In a transportmode, the drive wheel and casters extend for transporting the imagingsystem.

In one embodiment, the drive wheel is servo controlled and tied to auser drive system on the imaging system, which allows the system to feelweightless during transport.

In one embodiment, the drive wheel has an active servo-controlledsuspension to allow for smooth movement over thresholds, bumps in thefloor and ramps when transporting the system.

In certain embodiments, a mobile imaging system includes a drivemechanism as described above. Additional embodiments relate to methodsof imaging using a drive mechanism of the invention.

In preferred embodiments, the drive mechanism is extremely compact,which allows the entire drive system to be hidden from view, such asbeneath the gantry and gimbal assembly and inside the base, while notinterfering with operation of the imaging system.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Other features and advantages of the present invention will be apparentfrom the following detailed description of the invention, taken inconjunction with the accompanying drawings of which:

FIG. 1 is a side view of a mobile imaging system with a drive wheel andcasters extended and the base of the system raised off the floor;

FIG. 2 is a side view of the mobile imaging system with the drive wheeland casters retracted and the base lowered to the floor;

FIG. 3 is a bottom isometric view of the imaging system showing thedrive wheel and casters retracted and pads on the bottom surface of thebase that define a scan plane;

FIG. 4 is a side view of the mobile imaging system in a transport mode;

FIG. 5 is an isometric view of the mobile imaging system in a scan mode;

FIG. 6 is a top isometric view of the drive mechanism for an imagingsystem according to one embodiment;

FIG. 7 is an isometric view of the main drive assembly;

FIG. 8 is a bottom isometric view of the drive mechanism;

FIG. 9 is a rear isometric view of the drive mechanism;

FIG. 10 is a front isometric view of the drive mechanism;

FIGS. 11A and 11B are top isometric views of the main drive assembly;

FIGS. 12A and 12B are bottom isometric views of the drive mechanism;

FIG. 13 is a front view of the drive mechanism;

FIG. 14 is a side view of the drive mechanism;

FIG. 15 is a top view of the drive mechanism; and

FIG. 16 is a cross-sectional view of the main drive assembly.

DETAILED DESCRIPTION OF THE INVENTION

This application claims the benefit of U.S. Provisional Application No.61/313,299, filed Mar. 12, 2010, and is related to U.S. application Ser.No. 12/576,681, filed Oct. 9, 2009, and to U.S. Provisional ApplicationNo. 61/315,462, filed Mar. 19, 2010. The entire contents of theabove-referenced applications are incorporated herein by reference.

Referring to FIGS. 1-5, a mobile imaging system 100 according to oneembodiment of the invention includes a mobile base 20, a gimbal support30, a gantry ring 40, and a pedestal 50. The system 100 includes imagecollection components, such as a rotatable x-ray source and detectorarray or stationary magnetic resonance imaging components, that arehoused within the gantry ring 40. The system 100 is configured tocollect imaging data, such as, for example x-ray computed tomography(CT) or magnetic resonance imaging (MRI) data, from an object locatedwithin the bore of the gantry ring 40, in any manner known in themedical imaging field. As shown in FIGS. 1-3 and 5, the pedestal 50 isadapted to support a tabletop support 60 that can be attached to thepedestal 50 in a cantilevered manner and extend out into the bore of thegantry ring 40 to support a patient or other object being imaged. Asshown in FIG. 4, the tabletop support 60 can be partially or entirelyremoved from the pedestal 50, and the gantry ring 40 can be rotatedrelative to the base 20, preferably at least about 90 degrees, from animaging position (FIGS. 1-3 and 5) to a transport position (FIG. 4) tofacilitate transport and/or storage of the imaging system.

As illustrated most clearly in FIGS. 3 and 5, the system 100 includes adrive mechanism 70. The drive mechanism 70 is mounted beneath the gimbal30 and the gantry ring 40 and within the base 20. The drive mechanism 70also comprises a drive wheel 71 that can extend and retract between afirst extended position (FIG. 1) to facilitate transport of the imagingsystem 100, and a second retracted position (FIGS. 2 and 3) during animage acquisition procedure (e.g., scan). The drive mechanism 70includes a main drive (described in further detail below) that is gearedinto the drive wheel 71 when the drive wheel 71 is in the first extendedposition (FIGS. 1 and 3) to propel the imaging system 100 across a flooror other surface, and thus facilitate transport and positioning of thesystem 100. According to one aspect, the drive wheel 71 is decoupledfrom the main drive when the drive wheel 71 is in the second retractedposition (FIGS. 2 and 3), thus preventing the system 100 from backdriving the main drive gearbox and motor during an imaging procedure.

As is illustrated in FIGS. 3 and 5, the base 20 is a sturdy, generallyrectilinear support structure. The base 20 includes a central openingextending lengthwise along the base, and the drive mechanism 70 ispositioned inside the central opening. As seen in FIG. 3, the bottom ofthe base 20 includes a plurality of pockets that contain retractablecasters 21. The casters 21 can be spring-loaded and biased to extendfrom the bottom of the base 20 when the system is raised off the ground,as shown in FIGS. 1 and 4. When the drive wheel 71 is retracted and thesystem 100 is lowered to the ground, as shown in FIG. 2, the casters 21are retracted into their respective pockets. In an alternativeembodiment, an active drive system, rather than a passive spring-basedsystem, can drive the extension and retraction of the casters in theirrespective pockets.

The top of the base 20 is shown in FIG. 5, and includes a pair ofparallel rails 23 running lengthwise on the top surface of the base, oneither side of the central opening of the base. During an imaging scan,the gantry 40, gimbal 30 and drive mechanism 70 translate along animaging axis relative to the base 20, pedestal 50 and patient support60. Bearing surfaces, which can be located on or attached to the drivemechanism 50 and/or gimbal 30, mate with the rails 23 to guide thetranslation motion relative to the base. The drive mechanism 70 caninclude a scan drive (described in further detail below) that drives thetranslation motion of the drive mechanism 70, gimbal 30 and gantry 40relative to the base 20.

The base 20 can be made compact and relatively lightweight to improvethe portability and usability of the system 100. Minimizing the heightand width of the base 20 minimizes interference with the operator's feetas the operator approaches a patient on the support table. A furtheradvantage of this embodiment is that the wheels, including drive wheel71 and casters 21, retract within the base during imaging, and thuscannot interfere with the operator. The drive mechanism 70 in thisembodiment is small and compact, and is generally hidden beneath thegimbal 30 and gantry ring 40 and positioned inside the central openingof the base 20, and advantageously does not interfere with the operatoror with the loading/unloading of a patient or patient support table.Positioning the wheels within the base also minimizes the risk of injury(e.g., running over a person's foot) during transport of the system. Itwill be further noted that in this embodiment, the width of the base 20tapers at the end of the base supporting the pedestal 50. An advantageof this design is that it allows a cart or shuttle to more easilyapproach the pedestal-end of the system 100 in order to transfer apatient support table 60 to the top of the pedestal 50 for imaging, orto remove the support table 60 from the top of the pedestal 50 followingimaging. The shape and size of the base 20 and pedestal 50 can bedesigned to mate with the cart to facilitate the interchange of patientsupport tables. Suitable patient support tables and transport carts areknown in the art, and examples are described in the JUPITER systembrochure (November 2008) from TRUMPF Medezin Systeme GmbH & Co. KG ofPuchheim, Germany, the entire contents of which are incorporated hereinby reference.

In one embodiment, the width of the base 20 is approximately equal to orless than the width of the patient support table. At its widest (e.g.,from the outside of the caster pockets), the base 20 can be less thanabout 25 inches wide, and can be around 22 or 23 inches wide. Thecentral opening of the base can be about 13 inches across, or any othersuitable dimension to accommodate the drive mechanism 70. The base 20 isgenerally less than about 6 inches in height when the system is loweredon the floor. The drive mechanism 70 is preferably very compact tomaximize the translation motion of the gantry ring 40 relative to thebase 20 and the support table 60. In one embodiment, the gantry ring 40can translate at least about 40 inches to 48 inches.

Conceptually, the imaging system 100 according to this embodiment can beconsidered to include two separate sub-assemblies. The firstsub-assembly is comprised of the base 20, pedestal 50 and patient table60. The second sub-assembly includes the drive mechanism 70, the gimbal30 and the gantry ring 40. This second sub-assembly includes most or allof the imaging components on the gantry ring 40, and is generally muchheavier than the first sub-assembly. By way of example, for an x-ray CTscanning system, the gimbal and gantry sub-assembly can weigh on theorder of 1400 to 1500 lbs., whereas the base/pedestal/table sub-assemblytypically only weighs about 1000 lbs. or less.

According to one aspect, the drive mechanism 70 supports the weights ofthe gimbal 30 and gantry ring 40 during imaging procedures as well asduring transport of the system. The base 20 and pedestal 50 aresupported on the casters 21 during transport of the system. Duringimaging, the base 20 is lowered and can be supported on the ground. Thedrive mechanism 70 is configured such that even when the drive wheel 71is retracted (FIGS. 2 and 3), the wheel 71 still contacts the ground andsupports the weight of the gantry and gimbal sub-assembly. The drivemechanism supports at least a portion of the weight of the gantry andgimbal sub-assembly—i.e. greater than 0% and up to 100% of the weight ofthese components. In one embodiment, at least 50% of the weight ofgantry and gimbal is supported by drive mechanism 71. In otherembodiments, at least 60%, at least 70%, at least 80%, at least 90% andmore than 95% of the weight of the gimbal and gantry sub-assembly issupported by the drive mechanism 71.

With this arrangement, the comparatively heavier weight of thegimbal/gantry sub-assembly does not need to be supported by the base ofthe system, which means the base can be made smaller and lighter forimproved portability. Further, since the imaging gantry is supported atall times at least in part by the drive mechanism, the gantry cantranslate a relatively long distance along the length of the base whileminimizing the possibility of beam deflection, which can result invariations of the scan plane and negatively effect image reconstruction.As shown in FIG. 3, the bottom surface of the base 20 includes at leastthree pads 25 that define a single imaging plane. When the base 20 islowered to the floor, the base 20 rests on the pads 25, which define asingle reference plane for the base, pedestal and table assembly, whichare fixed relative to the pads 25. The pads 25 maintain this referenceplane even when there are elevation differences in the floor. The rails23 of the base, upon which the gimbal and gantry translate, aresimilarly fixed in relation to the pads 25, and define an imaging plane,parallel to the reference plane, for the imaging components of thegantry. According to one aspect, the drive mechanism 70 includes asuspension system (described further below) between the drive wheel 71and the gantry that supports the weight of the gimbal and gantry andallows the drive wheel to conform to elevation differences in the floorwhile the gimbal and gantry translate in the imaging plane defined bythe rails, further minimizing deflection of the imaging plane path ofthe imaging components.

During transport mode, the drive mechanism 70 extends the drive wheel 71downward as shown in FIGS. 1 and 4, which causes the base 20 to raiseoff the ground and the casters 21 to extend. As previously noted, thecasters 21 can be spring-loaded to extend when the base 20 is lifted offthe ground, or alternatively, they can be actively extended by asuitable drive apparatus. The drive mechanism 70 can include asuspension drive (described in further detail below) to drive theextension and retraction of the drive wheel 71. During transport mode,the drive mechanism 71, along with the gimbal 30 and gantry ring 40, cantranslate to the approximate center of the base 20, as shown in FIG. 4,so that these heavier components are approximately centered between thecasters 21. This helps improve the balance and stability of the systemduring transport. The gimbal 30 and gantry ring 40 can be rotated intotransport position, as shown in FIG. 4. A pin system can lock the drivemechanism 70, gimbal 30 and gantry ring 40 in place relative to the base20 so that the entire system can be easily transported. The drivemechanism's main drive, which drives the drive wheel 71, can beservo-controlled, and the system 100 can be driven, in both forward andreverse directions, in response to a user input command. The suspensionsystem of the drive mechanism 71 can be an active suspension system, asdescribed below, which can aid in driving the imaging system 100 overuneven surfaces, such as thresholds and ramps. Steering of the systemcan be achieved by pivoting the system 100 around the centrally-locateddrive wheel 71, using the casters 21 for balance and support. A handleor other steering mechanism can be provided on the system (such as onthe gimbal, gantry, or pedestal) to assist in driving the system. Astrain gauge, throttle, button or other user-input mechanism located onthe system can provide servo-feedback down to the drive mechanism tocontrol the driving of the drive wheel 71. In one embodiment, shown inFIGS. 1-3 and 5, the system 100 can include a display system 31 thatincludes a camera on one side of the system and a display screen, suchas an LCD display, on the opposite side of the system that allows theoperator positioned behind the system to see obstacles in front of thesystem, which further assists the transport of the system. The system100 can include a collision detection system, such as an audio or visualrange-finder device, to further assist in transporting the device.

Turning now to FIGS. 6-16, a drive mechanism 70 in accordance with oneembodiment of the invention is shown. The drive mechanism 70 can includethree drive systems: a main drive assembly 73 that is coupled to anddrives the drive wheel 71 for transporting the imaging system, a scandrive assembly 75 for translating the imaging components relative to thesystem base during an imaging scan, and a suspension drive assembly 77that controls the extension and retraction of the drive wheel 71.

The main drive 73 is shown most clearly in FIGS. 7, 11A, 11B, and 16,and includes a motor 81, a sprocket 83 that can be connected by a drivechain 89 (FIG. 6) to the drive wheel 71, a gearbox 82, a sliding yoke84, and a brake mechanism 86. As noted above, the main drive 73 isengaged to the drive wheel 71 when the wheel is extended in transportmode, and is de-coupled from the drive wheel when the wheel is retractedduring an imaging mode. The engagement and disengagement of the drivewheel 71 is accomplished by the sliding yoke 84, which is connected to amain drive decoupling linkage 91 (FIGS. 12B and 13). As the drive wheel71 retracts and extends, the decoupling linkage 91, which can be arotating piston and sleeve assembly, causes the yoke 84 to reciprocate,as shown by the arrow in FIG. 7. This causes a sliding spline 85 (FIG.16), connected to the yoke 84, to move in and out of mating engagementwith the sprocket 83, thereby controlling the engagement anddisengagement of the drive wheel 71 from the motor 81 and gearbox 82.The yoke 84 and spline 85 can be spring-biased into a disengagedposition, and only when the drive wheel is in an extended position doesthe wheel 71 become engaged to the main drive.

The main drive 73 also includes a brake mechanism, which includes arotating brake disc 86, a spring-loaded brake rod 87, and a brakesolenoid 88. The brake disc 86 can be coupled to the sprocket 83. Thebrake rod 87 can be biased to extend beyond the brake disc 86, as shownin FIG. 7, which prevents the sprocket 83 and drive wheel 71 fromrotating. The brake mechanism thus functions similar to a parking brakein an automobile. When the solenoid 88 is energized, it drives the brakerod 87 to retract away from the brake disc 86, which is then free torotate along with the sprocket 83 and drive wheel 71. An importantsafety feature of this design is that if the imaging system 100 losespower, the brake rod automatically extends to stop the motion of thedrive wheel 71.

The scan drive assembly 75 is shown in FIGS. 6, 8-10 and 12A-13. Thescan drive assembly 75 drives the translation of the drive mechanism 70,gimbal 30 and gantry ring 40 relative to the base 20. In thisembodiment, the scan drive assembly 75 is mounted adjacent the maindrive assembly 73 and drive wheel 71. All of these components aremounted beneath the gimbal 30 and gantry ring 40 in a compact space,generally in the opening within the base 20. The scan drive assembly 75in this embodiment includes a motor 92 and a belt drive 93, which isshown most clearly in FIGS. 8 and 10. The belt drive 93 mates with abearing surface on the base 20 in order to effect the translation of thedrive mechanism, gimbal and gantry ring relative to the base. In oneembodiment, the belt drive 93 mates with a bearing surface, which can bea lip or rail (not shown), provided on an interior wall of the centralopening of the base 20 (FIGS. 3 and 5). A belt 94 is secured to thebearing surface and is looped through the belt drive 93, where it mesheswith a pulley driven by the scan drive motor 92, as shown in FIGS. 8 and10. The rotation of the scan drive motor 92 thus causes the scan driveassembly 75 to traverse along the length of the belt 94, and therebytranslate the gantry, gimbal and drive mechanism relative to the base.The belt drive 93 can be servo-controlled, with a linear encoder device,and have substantially zero or minimal backlash, to provide precise,controlled fine-scanning of the imaging components relative to the baseand patient support table. Any suitable configuration for achievingtranslation using a scan drive disposed within the drive mechanism canbe employed.

The suspension drive assembly 77 is shown most clearly in FIGS. 6, 8-10,and 12A-15. The suspension drive assembly comprises a motor 95 andgearbox 96 that drive the rotation of a lead screw 97. A lead screw nut98 translates with the rotation of the lead screw 97, as indicated bythe “nut travel” arrow shown in FIG. 6. The lead screw nut 98 ismechanically coupled to a pair of rail carriages 99, so that thetranslation of the lead screw nut 98 causes the rail carriages 99 totranslate on a pair of rails 101 that are fixed to the upper plate 102of the drive mechanism 70, as shown in FIG. 8. The rail carriages 99 areeach connected to one end of a spring 103, which can be a gas spring, asshown in FIG. 8. The other end of each spring 103 is connected arespective swing arm 104 that can pivot with respect to the drivemechanism around an pivot axis 106. As can be seen in FIG. 8, forexample, the translation of the rail carriages 99 causes the springs 103to articulate with respect to the rail carriages 99 and the swing arms104, which in turn causes the swing arms 104 to pivot, as showngenerally by the arrow in FIG. 8. The drive wheel 71 is mounted betweenthe two pivoting swing arms 104, so that the translation of the railcarriages 99 and the resulting pivoting motion of the swing arms 104causes the drive wheel 71 to extend and retract relative to the upperplate 102 of the drive mechanism 70.

As can be seen in FIGS. 12A and 12B, the main drive 73 can be mounted tothe swing arms 104. In this way, as the rail carriages 99 translatecausing the swing arms 104 to pivot, the main driveengagement/disengagement linkage 91, which connects the upper plate 102of the drive mechanism 71 to the sliding yoke 84 of the main drive 73,acts on the sliding yoke 84 to selectively engage and disengage the maindrive 73 to and from the drive wheel 71. As previously discussed, in oneembodiment, the drive wheel 71 is engaged to the main drive 73 only whenit is in an extended position—i.e., when the swing arms 104, main drive73 and drive wheel 71 are pivoted down and away from the upper plate 102of the drive mechanism 70. When the drive wheel 71 is retracted—i.e.,the swing arms 104, main drive 73 and drive wheel 71 are pivoted upwardstowards the upper plate 102, the yoke 84 slides back to disengage themain drive 73 from the drive wheel 71.

It will be noted that when the drive wheel 71 is retracted, the base 20automatically lowers to the ground and rests on pads 25, as shown inFIGS. 2, 3 and 5. During an imaging scan, the weight of the gimbal 40and gantry 30 remains supported by the drive wheel 71, which is able tofreely-rotate as the gimbal and gantry translate on the rails 23 of thebase. One advantage of this configuration is that the heavy gimbal andgantry ring assembly can be easily moved manually relative to the base,such as may be required in order to quickly access a patient during anemergency situation.

The springs 103 function as a suspension system between the drive wheel71 and the gimbal 30 and gantry ring 40, which are supported by thedrive wheel 71 during both transport and imaging modes. The springs 103can contract to allow the wheel 71 to conform to elevation differencesin the floor during an imaging scan, while the drive mechanism 70,gimbal 30 and gantry ring 40 translate on the base 20 during an imagingscan. This can greatly reduce or eliminate deflection of the scan planepath of the imaging components during the fine movement scan. Duringtransport of the system 100, the springs 103 can facilitate transport ofthe system over uneven surfaces, including door thresholds and ramps,for example. In one embodiment, the suspension system is an activesuspension system that can maintain a controlled force between the drivewheel and the floor. In this embodiment, the springs 103 and suspensiondrive assembly 77 can include an active servo-control system that cancontinually adjust the translation of the rail carriages to maintain asubstantially constant spring displacement, and thus maintain asubstantially constant force between the wheel and the floor. As shownin FIGS. 12A and 13, for example, an encoder 105 can be provided on atleast one of the swing arms 104 to measure the displacement of the swingarm 104 and spring(s) 103 relative to the upper plate 102. The encoder105 can provide a feedback signal to the suspension drive 77 to makecontinual fine adjustments and control the force between the wheel andthe floor.

The drive wheel 71 can comprise a suitable elastomeric material that israted to safely support the weight of the imaging components in thegimbal and gantry ring assembly. For example, the wheel can be rated tosupport about 1900 lbs. A softer durometer material for the wheel willprovide better grip and minimize the risk of slippage, but may not berated to support the required weights.

An advantage of the present drive mechanism 71 is that it is easilyaccessible for servicing and repair. For example, the drive wheel can beextended to raise the system off the floor and provide easy access toany components of the drive mechanism 71. If the drive mechanism 71needs to be removed, the system can be put on blocks, and the entiredrive mechanism can be taken out at once, such as by removing the upperplate of the drive mechanism from the bottom of the gimbal 30.

While the invention has been described in connection with specificmethods and apparatus, those skilled in the art will recognize otherequivalents to the specific embodiments herein. It is to be understoodthat the description is by way of example and not as a limitation to thescope of the invention and these equivalents are intended to beencompassed by the claims set forth below.

What is claimed is:
 1. A mobile imaging system, comprising: a base; agantry having one or more imaging components; a drive mechanism thattranslates the gantry relative to an object being imaged in an imagingmode and propels the mobile imaging system across a surface in atransport mode; a plurality of casters that are retracted into the basein the imaging mode and are extended from a bottom surface of the basein the transport mode; a display system that includes a camera on afirst side of the mobile imaging system and a display screen on a secondside of the mobile imaging system opposite the first side.
 2. The mobileimaging system of claim 1, wherein the drive mechanism comprises: adrive wheel; and a main drive mechanically coupled to the drive wheelfor propelling the imaging system, including the base and one or moreimaging components, across a surface in a transport mode; and atranslation mechanism that translates the one or more imaging componentsalong an axis relative to the base in an imaging mode, the drive wheelsupporting the one or more imaging components at least in part in boththe transport mode and the imaging mode.
 3. The mobile imaging system ofclaim 2, wherein the translation mechanism comprises a scan drive thattranslates the one or more imaging components along an axis relative tothe base to provide an imaging scan.
 4. The mobile imaging system ofclaim 2, further comprising: a suspension drive that extends the drivewheel relative to a bottom surface of the base when the imaging systemis in a transport mode and retracts the drive wheel relative to thebottom surface of the base when the imaging system is in an imagingmode.
 5. The mobile imaging system of claim 2, wherein the drivemechanism is mounted to the imaging components and supports the weightof the imaging components but not the base during transport of thesystem.
 6. The mobile imaging system of claim 2, wherein the drive wheelretracts for lowering the base onto floor during an imaging mode andextends raising the base from the floor during a transport mode.
 7. Themobile imaging system of claim 2, wherein the weight of the imagingcomponents is supported by the drive mechanism during both transport andimaging modes.
 8. The mobile imaging system of claim 2, furthercomprising a rail system on which the gantry translates relative to thebase during an imaging scan.
 9. The mobile imaging system of claim 2,further comprising a suspension system that reduces or eliminatesdeflection of the scan plane path of the imaging components during theimaging scan.
 10. The mobile imaging system of claim 9, wherein thesuspension system allows the drive wheel to conform to elevationdifferences in the floor while a rail system on the base maintains theplane of the imaging components.
 11. The mobile imaging system of claim10, wherein the suspension system maintains a controlled force betweenthe drive wheel and the floor.
 12. The mobile imaging system of claim10, wherein the suspension system comprises an active suspension system.13. The mobile imaging system of claim 2, wherein the drive wheel andcasters are located beneath the base and do not interfere with a userapproaching the base of a table system mounted to the base.
 14. Themobile imaging system of claim 1, wherein the weight of the base issupported by the casters in transport mode.
 15. The mobile imagingsystem of claim 1, wherein the drive mechanism is mounted at leastpartially inside and beneath the base.
 16. The mobile imaging system ofclaim 1, wherein the display system is configured to enable a userlocated adjacent to the second side of the mobile imaging system to seeobstacles located in front of the first side of the mobile imagingsystem in transport mode.
 17. The mobile imaging system of claim 1,further comprising an active drive system that drives the extension andretraction of the casters.
 18. The mobile imaging system of claim 1,wherein the base defines a reference plane for the translation of thegantry when the casters are retracted into the base.
 19. The mobileimaging system of claim 18, further comprising at least three pads thatare attached to the bottom of the base and sit on the floor to definethe reference plane.